(1) Field of the Invention
The present invention pertains to a direct vent gas fireplace that combines in a self-contained supporting outer shell beneficial features such as a directional flue pipe, a concealed exhaust opening in the fireplace firebox and a supply of vent air adjacent to the bottom of the fireplace firebox without significantly detracting from the heat exchange capabilities of the fireplace.
(2) Description of Related Art
Direct vent gas fireplaces typically include a firebox surrounding a heat chamber of the fireplace, where the firebox itself is surrounded by an outer shell. The firebox is typically constructed of left and right metal panels, top and bottom metal panels and a back panel that are connected together in a box-like configuration. The front of the firebox is left open providing access into the heat chamber of the firebox. The heat chamber contains a grate supporting a gas burner assembly which is usually concealed by gas logs. An exhaust opening is provided through the back panel of the firebox toward the top of the heat chamber to exhaust combustion fumes from the heat chamber.
The panels of the firebox are usually supported by metal walls of the surrounding outer shell of the fireplace. The outer shell is typically constructed of left and right side walls and a back wall that are spaced outwardly from the side panels and back panel of the firebox, together with opposite top and bottom walls that are spaced from the top and bottom panels of the firebox. Apart from the front access opening of the firebox, the firebox is usually completely enclosed by the outer shell walls and is supported in the outer shell with there being a void or spacing between the panels of the firebox and the walls of the outer shell. The spacing functions as a heat exchange volume surrounding the firebox in the outer shell. Vent panels are usually provided on the fireplace above and below the access opening to the firebox. An electric blower is positioned in the heat exchange volume where it will draw in ambient room air through the bottom vent of the fireplace and force a flow of air through the heat exchange volume and around the firebox and finally out through the top vent panel of the fireplace.
As air is cycled around the firebox panels by the blower, the heat of combustion in the heat chamber of the firebox is transferred through the firebox panels to the air cycled through the heat exchange volume. In this manner, the ability of the fireplace to heat the ambient air of the room in which the fireplace is positioned is optimized. Understandably, by increasing the interior surface area of the firebox panels that are directly subjected to the heat of gas combustion in the firebox heat chamber and by increasing the exterior surface area of the firebox panels that transfer the heat of combustion to the ambient room air cycled around the firebox, the ability of the fireplace to heat ambient room air is enhanced.
Over the years several structural features have been added to the typical gas fireplace to improve their combustion and versatility. For example, direct vent gas fireplaces have been developed that provide a supply of venting air from outside the building containing the fireplace directly to the firebox heat chamber. Direct vented air is typically more rich with oxygen than the ambient air of the room in which the fireplace is positioned and therefore enhances the combustion of the gas fireplace. The direct vented air of some fireplaces is provided through an air pipe that is concentric with and surrounds an exhaust pipe that is exhausting combustion fumes from the fireplace heat chamber to the building exterior. However, in some prior art direct vent gas fireplaces a system of conduits channels the vent air through the heat exchange volume between the firebox and the outer shell of the fireplace to inlet ports that supply the vent air to the heat chamber of the fireplace. The presence of the vent air conduits in the heat exchange volume of the fireplace obstructs the flow of ambient room air through the heat exchange volume and thereby detracts from the exchange of heat from the firebox panels to the flow of air cycled through the heat exchange volume by the fireplace blower.
Gas fireplaces have also been developed with an angled flue pipe that not only could be directed upwardly from the heat chamber of the fireplace as in conventional fireplaces, but could also be directed horizontally from the heat chamber to exhaust combustion fumes from the heat chamber out through a side wall of the building containing the fireplace. However, the angled flue pipe connected to the fireplace outer shell required extra available room outside the fireplace outer shell to accommodate the angled flue pipe. This, at times, would require that the fireplace be moved out from the wall of the room containing the fireplace thereby decreasing the rooms floor space, or required a larger enclosure of the fireplace flue outside the building containing the fireplace to accommodate the angled flue pipe, thus increasing the costs involved in installing the fireplace.
In addition, connecting an angled flue pipe to a fireplace to communicate the flue pipe with the heat chamber of the fireplace firebox would often require the addition of an angled firebox panel extending upwardly from the top edge of the back panel to the rear edge of the top panel of the firebox. The exhaust opening communicating with the angled flue pipe would be provided in the angled panel. However, the angled panel would extend downwardly from the top panel of the firebox and would usually be visible through the access opening of the firebox. Thus, the exhaust opening of the firebox would be viewable from the room containing the fireplace, detracting from the aesthetic appearance of the fireplace. A system of horizontal and vertical baffle plates were employed in the firebox heat chamber to conceal the exhaust opening. The baffles were connected between the side panels and the back panel of the firebox and between the side panel and the top panel of the firebox, concealing the exhaust opening while providing a flow path for combustion fumes from the heat chamber to the exhaust opening. However, the system of baffles had the detrimental effect of shielding portions of the firebox panel interior surfaces from the heat of combustion and thereby detracted from the ability of the fireplace to heat ambient room air circulated around the firebox.
What is needed to overcome the disadvantages associated with prior art direct vent gas fireplaces is a direct vent gas fireplace constructed with the beneficial features of an angled directional flue pipe that does not require additional space outside the fireplace outer shell to accommodate and support the angled flue pipe, an exhaust opening baffle that covers the exhaust opening from view but does not shield the firebox panels from the combustion heat in the heat chamber, and a system for directing vent air to the heat chamber without significantly obstructing the flow of ambient room air through the heat exchange volume of the fireplace.
The basic construction of the direct vent gas fireplace of the invention is similar to that of prior art gas fireplaces in that it includes a firebox supported in and surrounded by an outer shell and an angled flue pipe that enables the outlet end of the flue pipe to be directed either vertically or horizontally. However, the gas fireplace of the invention includes novel structural features that improve its efficiency in transferring heat of combustion to ambient room air cycled through the fireplace and also provide the fireplace with a self-contained, supporting structure for the angled flue pipe that contains a majority of the flue pipe within the outer shell and therefore can be installed in a home or building without having to accommodate and support an angled flue pipe projecting from the fireplace.
The fireplace is basically constructed from formed sheet metal panels that are connected together by sheet metal screws, rivets, spot welds, crimping or other equivalent means of connection. The firebox is comprised of a plurality of panels that surround a heat chamber of the firebox that is accessible through a front opening of the fireplace. The heat chamber contains the gas burner as well as the decorative grate and the gas logs that cover the gas burner. Air vent openings are provided through a back panel of the firebox and a combustion fume exhaust opening is provided through an angled back panel.
The outer shell encloses the firebox and supports the firebox in the outer shell in a suspended manner that creates a heat exchange volume between the exterior of the firebox and the interior of the outer shell. The outer shell includes a plurality of walls that surround the firebox. Top and bottom vent panels extend between the outer shell side walls above and below the access opening of the firebox. The outer shell also includes an electrically operated blower that is selectively activated to draw in ambient room air through the lower vent panel and cycle the air around the firebox in the heat exchange volume of the outer shell before forcing heated air out through the upper vent panel. The back of a top wall of the outer shell and the top of a rear wall of the outer shell are joined together at a right angle along a top, rear edge of the outer shell. The top wall has a rectangular opening at its back edge and the rear wall also has a rectangular opening at its top edge. The two rectangular openings intersect each other and provide sufficient clearance for the flue pipe of the fireplace whether the flue pipe extends vertically or horizontally.
The flue pipe is an angled flue pipe constructed similar to those of the prior art. The flue pipe includes a center exhaust pipe and a concentric air pipe that surrounds the exhaust pipe. Both the exhaust pipe and the air pipe have the same angled configuration. The exhaust pipe is secured around and communicates with the exhaust opening in the angled back panel of the firebox. The flue pipe can be connected to the firebox in two positions of the flue pipe relative to the firebox. In one position of the angled flue pipe, the exhaust pipe and air pipe extend vertically through the rectangular opening in the outer shell top wall. In the second position of the flue pipe, both the exhaust pipe and air pipe extend horizontally through the rectangular opening in the outer shell rear wall. In both positions of the flue pipe it is primarily contained inside the outer shell.
The novel construction of the gas fireplace of the invention includes a flue pipe plate that closes the rectangular openings in the outer shell top wall and outer shell rear wall, and also provides support to the flue pipe in both positions of the flue pipe relative to the firebox. The flue pipe plate is basically comprised of two rectangular sections that are bent at a right angle relative to each other. Only one of the two sections of the flue pipe plate has an opening and the opening is dimensioned to receive the flue pipe in a snug fit. The pipe plate can be attached to the outer shell in two positions of the plate relative to the shell. In a first position of the pipe plate the section with the opening is attached to the outer shell top wall and the other section of the pipe plate closes the opening in the outer shell rear wall. The pipe plate is attached to the outer shell in this position when the angled flue pipe attached to the firebox projects vertically from the outer shell through the pipe plate opening. In the second position of the pipe plate the section of the plate with the opening is attached to the outer shell rear wall and the other section of the plate closes the opening in the outer shell top wall. This positioning of the pipe plate is used when the angled flue pipe is attached to the firebox with the flue pipe projecting horizontally from the outer shell. In either position of the pipe plate, the pipe plate opening surrounds the end of the angled flue pipe that projects from the outer shell and provides support to the flue pipe. In addition, the outer shell together with the flue pipe plate contain the angled portion of the flue pipe within the outer shell.
The novel construction of the fireplace also includes a baffle in the fireplace heat chamber that conceals the exhaust opening from view without appreciably shielding the interior of the firebox from the heat of combustion generated in the heat chamber. The baffle has a simple and inexpensive one-piece construction. The baffle is generally planar with a rectangular perimeter edge and a pair of spacer arms that project at angles from opposite sides of the baffle. The arms are connected to the angled pack panel of the firebox on opposite sides of the exhaust opening. The baffle is dimensioned just large enough so that it will conceal the exhaust opening from view through the access opening of the firebox. In this manner, the baffle aesthetically conceals the exhaust opening from view, but does not appreciably shield the interior surface of the firebox panels from the heat of combustion in the heat chamber as do many prior art baffles that are connected to the firebox panels and extend completely across the width of the firebox.
The gas fireplace of the invention is also provided with a vent air column that communicates with the vent air pipe of the flue pipe and provides a direct path from the vent air pipe to the air vent openings of the firebox. The air column is centered behind the firebox and extends downwardly from the air pipe that surrounds the exhaust pipe of the fireplace directly to a pair of air vent inlets that pass through the firebox back panel adjacent the bottom of the firebox. By constructing the air column in this manner, the air column provides a direct path of vent air passing through the air pipe of the flue to the vent air inlets of the firebox which minimizes any transfer of heat from ambient room air circulated through the heat exchange volume to the cooler vent air passing through the air column and also minimizes any obstruction to the flow of ambient room air through the heat exchange volume around to the firebox.
The direct vent gas fireplace of the invention constructed as described above provides the benefits of positioning the angled flue pipe of the fireplace within the fireplace outer shell thereby eliminating the need for additional structure outside the fireplace to accommodate and support the angled flue pipe, concealing the exhaust opening in the firebox from view through the firebox access opening without appreciably shielding the interior surfaces of the firebox from the heat of combustion in the firebox heat chamber, and providing vent air to the heat chamber of the firebox without appreciably obstructing or cooling the flow of ambient air through the heat exchange volume of the fireplace.